Animal Nutrition and Productions: Series II

The Food and Agriculture Organization of the United Nations estimates that by 2050, there will be a 58% increase in dairy consumption and a 73% increase in meat and egg consumption, worldwide, which would put additional pressure on the availability of natural resources. In addition, to feed almost two billion more people by 2050, it is necessary to sustainably increase the yield of agri-food products of animal origin [1]. Within such a context, raising animals and especially providing the animal feed quality and quantity required will be a challenge in line with the three pillars of sustainability (economy, social, environment), which will have a far-reaching impact on food prices, human nutrition, and the global economy. It is undeniable that solving these constraints is complex and multifactorial, in order to securely raise animals and obtain safe and affordable food of animal origin to meet the increased demand.

The key element of the sustainability of animal food production is animal nutrition, which affects almost every sector of animal production: performance and efficiency, product quality and safety, health and welfare, farm economic viability, and environmental protection.

This Special Issue “Animal Nutrition and Productions: Series II” is a collection of 23 articles that capture the latest knowledge and innovations in animal nutrition and production and cover current topics through multi- and trans-disciplinary approaches, such as additives and novel feeds, animal productivity, reproductive efficiency, animal welfare and health, and product safety and quality. This collection consists of 19 original research articles, 3 review articles, and a meta-analysis, explored by 143 researchers from many different countries (Romania, China, Mexico, Poland, Czech Republic, Italy, and Canada). Most articles were written by authors from Romania (12 articles), followed by authors from China (4 articles), Mexico (3 articles), Italy, Poland, the Czech Republic, and Saudi Arabia (1 article each).

The research topics addressed by the authors focus on the evaluation of the effect of different nutritional strategies on the productive performances, nutritional value, and safety of agro-food products of animal origin (milk; eggs: chicken and quail; meat: chicken broiler, duck, mutton, veal, pork), the welfare and health of the animals, their reproductive function, and also the effect on the environment. Other researchers had objectives such as an evaluation of the quality of rabbit meat in relation to the gender and type of muscle, an analysis of the quality of polyfloral honey, an analysis of the quality of some dairy products, an evaluation and monitoring of pollutants in feed and milk, a standardization of the use of antibiotics in pig farms, and also studying aspects related to the preservation of biodiversity and the conservation of genetic resources.

Nutritional strategies play an essential role in determining animal productivity and the nutritional and safety properties of animal products, using some key indicators: the type and composition of the diet and the balance of dietary macronutrients, vitamins, and minerals. In addition, the use of alternative feed sources rich in nutrients and bioactive compounds contributes to increasing the sustainability of animal production, improves animal health, and leads to obtaining animal products with improved nutritional profiles which are also safe for consumers [2].

The scientific papers included in this Special Issue discuss the identification of novel feed ingredients, the optimization of nutrient availability, precision feeding techniques in meeting the nutritional requirements of animals, and different feeding strategies for ruminants, poultry, and pigs.

Ruminant nutrition research focuses on evaluating the effect of diet on milk and dairy products’ quality, reproductive performance in goats and rams, and the influence of feed additives and meat yield and quality in lambs and calves.

Studies on poultry feeding strategies (laying hens, laying quails, broilers, and ducks) have focused on four main topics, namely feed additives, bioproductive performance, agro-food product quality (eggs and meat), and fowl health and welfare.

In the case of pigs, feeding strategies have focused on the opportunity of using alternative feed sources, and their effect on yield, meat quality, and environmental protection, but also aspects related to the need of regulating the use of antibiotics in pig farms in relation to maintaining and promoting public health.

The nutritional quality and content of bioactive compounds, with the potential to improve consumers’ health, in milk and milk products are influenced by certain factors, with the most important being those related to animal nutrition and feeding. Thus, milk obtained from pasture-raised cows (generically called grass milk) is sought after and preferred by consumers because they consider it healthier than that obtained from cows fed indoors on stock feed [3].

In this respect, Rațu et al. [4] evaluated the effect of grazing on the chemical composition and fatty acid profile of milk and yogurt compared to that of cows on an indoor feeding system with TMRs (total mixed rations) based on corn silage, grass hay, and concentrates. Grazing cows provided better milk quality, especially in terms of fatty acid profile, i.e., polyunsaturated fatty acid (PUFA) content (CLA: conjugated linoleic acid, LA: linoleic acid, and ALA: α-linolenic acid). In addition, the fatty acid profile of yogurt was improved compared to the original profile in raw milk, due to the increase in the proportion of PUFAs resulting from fermentation processes.

At the same time, the studies carried out by Maciuc et al. [5] demonstrated that cheeses marked with the quality label “mountain product”, obtained from animals that had access to pasture, had better nutritional and safety properties than the conventionally produced cheeses, i.e., a higher content of minerals (Ca, P, Fe) and PUFA, which made better values of the health lipid indices possible (atherogenic index, thrombogenic index, ratio of hypocholesterolemic/hypercholesterolemic fatty acids) compared to conventional cheeses. In conclusion, cheeses bearing the “mountain product” quality label are more nutritious, contribute to maintaining and promoting the health of consumers, and are obtained in a sustainable production system where mostly local inputs are used as feeding resources.

Milk, in addition to its nutrient and bioactive compound content, can be contaminated with a number of pollutants with adverse effects on the consumers’ health [6]. The occurrence of pollutants in feedstuffs depends on the pollution profile of the geographical area, and the transfer of pollutants from feed to milk is influenced by the amount and profiles of dietary pollutants, by pollution sources, and by the interaction between some categories of pollutants [7].

The studies carried out by Rodriguez-Cordero et al. [8] and Carrillo-Muro et al. [9] focused on the use of calcium propionate (gluconeogenic compound) in the diet of growing calves and finishing lambs, respectively, with the aim of increasing dietary energy availability and thus improving both growth performance and body fat reserves, as well as meat quality, without compromising animal health. The studies concluded that calcium propionate (CaPr) is an effective feed additive that provides additional energy to growing animals. Early diet supplementation of growing calves with CaPr (20 g/calf/day) increased average daily gain (ADG), body mass (BW), feed efficiency (FCR), and body fat reserves, while the metabolic profile also improved (blood urea nitrogen decreased and the activity of some enzymes increased) [8]. In lambs, supplementation of the finishing diet with CaPr (10 g/lamb/day) for a period of 24 to 28 days prior to slaughter can improve growth performance and carcass weight without affecting organ mass or meat quality [9].

Numerous studies have demonstrated the importance of nutritional factors in the reproductive activity of animals. Adopting correct feeding strategies positively influences puberty onset, ovulation rate, embryo survival, and semen quantity and quality. In this context, Pascal et al. [10] concluded that supplementing rams’ diets with fat-soluble vitamins (A, D, E) and trace elements (Zn, Fe, Mn, Cu, Co, I, Se) significantly improved reproductive performance, as a result of increasing ejaculate volume and improving sperm quality (increased concentration of viable spermatozoa and decreased proportion of abnormal spermatozoa), and increased testosterone levels, which improved mating behavior. This topic was also addressed by Mohammed and Al-Suwaiegh [11] who supplemented the diet of pregnant goats (4 weeks prior to mating and 4 weeks post partum) with Nigella sativa seeds (10.0 and 20.0 g seeds of N. sativa per kg of diet) with the aim of improving ovarian follicle development, health status, and milk composition. Such a feeding strategy was effective in improving feed conversion, milk nutritional quality, metabolic profile, and ovarian follicle development.

In addition to improving poultry productivity, there is high interest in enhancing the nutritional and sensory qualities of poultry products (eggs and meat), thereby influencing consumers’ preferences and choices, as shown in some of the papers published in this Special Issue. The meta-analysis conducted by Orzuna-Orzuna et al. [12] led to the conclusion that supplementing the diet of laying hens with essential oils improves the productive performance (increases egg yield and egg mass and decreases the feed conversion ratio) and egg quality (mineral shell thickness and strength and intensity of the yolk color). In addition, dietary inclusion of essential oils improved blood serum antioxidant status and intestinal morphology in laying hens. The best results were obtained when the primary bioactive compounds of the essential oils were menthol, cinnamaldehyde, terpinen-4-ol, or mixtures of bioactive compounds. In contrast, studies by Li et al. [13] demonstrated that replacing vitamin D3 in the diet of laying hens with 25-hydroxyvitamin D3 (125 µg/kg) did not influence the production performance, whilst it negatively impacted shell thickness and weight and improved bone strength (femur and tibia) throughout the late laying period.

The most important and suitable sources of protein for poultry are soybean products and by-products, which due to cultivation requirements have become progressively more limited and expensive. In this context, lately, research attention has focused on the identification and validation of alternative protein sources for animal feed. According to Struti et al. [2], the introduction of white lupine beans from low-alkaloid varieties into the diet of laying quails (250 g/kg), in association with specific exogenous enzymes, makes the major substitution of soybean meal in the diet (by more than 60%) possible without affecting egg yield, egg weight, physico-chemical parameters of egg quality, or FCR. Meanwhile, white lupine beans can be used as part of a strategy to improve the nutritional quality of eggs by increasing the content of omega-3 fatty acids and carotenoids in the yolk and lowering the cholesterol concentration.

Similarly, Bondar et al. [14], following the analysis of sources in the literature, state that spirulina (Spirulina platensis) can be used as an alternative feed source for fowl, being widely recognized as a valuable source of protein (55–70%), essential fatty acids (18–20%), various vitamins (such as thiamin, riboflavin, pyridoxine, vitamin B12, vitamin C), and numerous bioactive compounds (tocopherols, chlorophyll, carotenoids, phenols), with positive effects on productive performance, intestinal integrity, and immunity.

In recent years, there has been increased interest in improving the production performance of animals, maximizing the efficiency of feed utilization, and increasing the safety of products intended for human consumption [15]. Trace elements are essential nutrients in improving the growth performance of fast-growing broilers. In this sense, Lv et al. [16] investigated the effects of replacing inorganic trace elements with organic ones (sucrose-chelated trace elements) in broiler diets and concluded that this advanced mineral chelation technology can reduce the trace element requirements of broilers. Thus, using chelated trace elements (Cu, Fe, Zn, and Mn) at a dose of 1–1.5 g/kg instead of inorganic trace elements (2.0 g/kg diet) did not affect growth performance, dietary energy, nutrient utilization, antioxidant capacity, or trace element deposition in the liver. It turns out that organic trace elements can reduce mineral excretion in broilers, which can decrease environmental pollution.

Although global poultry meat consumption is following an upward trend, consumers blame the poor sensory properties and low nutritional value of the meat provided by fast-growing chickens. To respond to the new market preferences, the research carried out by Usturoi et al. [17] evaluated the effect of dietary protein supplementation on growth performance and meat quality in slow-growing broilers (Hubbard JA757 hybrid). The results demonstrated that the level of crude protein increase in the diet of chickens (+0.5% CP in the growth phase and +1.0% CP in the finishing phase, compared to the recommendations of the Hubbard company) led to an improvement in the production performances (LW and FCR) of meat and carcass quality (more breast and thigh %).

A limiting factor for the development of animal production is represented by the shortage of feed ingredients. In tropical and subtropical areas, rubber trees are widespread and their seeds are often discarded and not redeemed effectively. Rubber seed oil contains important amounts of n-3 PUFA (approx. 26% of total fat), which gives them the opportunity to be used in animal feed not only as a concentrated source of energy but also as a potential resource to obtain food products of animal origin enriched in n-3 PUFA (functional foods). Zhao et al. [18] demonstrated that replacing soybean oil with rubber seed oil reduced abdominal fat deposition and increased n-3 PUFA levels in meat without affecting the growth performance of Pekin ducks. In addition to nutritional factors, the housing system can influence productive performance, carcass traits, and bone composition in ducks. Krunt et al. [19] revealed that ducks reared on deep litter with access to a swimming pond had a higher live weight and better feed conversion ratio but a lower proportion of breast in the carcass structure than ducks maintained on deep litter without access to a pond. Housing conditions did not affect the fracture toughness of the fowl tibia and femur; however, ducks that had access to the pond had more Ca and Mg in the tibia and more Mg in the femur.

Classic diets for pig nutrition are based on a mixture of corn and soybean meal as the main sources of energy and protein, which correspond very well to the nutritional requirements of pigs. However, there is currently a growing discrepancy between yield, availability, and demand for feed. Thus, the identification and use of locally accessible resources are necessary to ensure animal feed requirements. Roguski et al. [20] propose the partial substitution of cereal grains and protein components in pig feed with Wet Distillers’ Grains plus Solubles (WDGSs), which are by-products in the bio-ethanol industry and are characterized by a high concentration of crude protein and crude fat (% of DM—dry matter). The authors concluded that WDGSs can be used in the liquid feeding of pigs in a proportion of up to 15% of the DM, without affecting the pig performance, carcass traits, meat quality, proximate composition, or physical–chemical traits of pork. Similar topics were also addressed in the papers of Chiofalo et al. [21] and Mihaila et al. [22]. Chiofalo et al. [21] evaluated the agronomic traits, chemical composition, fatty acid profile, and in vitro fermentation characteristics of twelve varieties of Amaranthus spp. grown in a semi-arid Mediterranean area. Among the varieties studied, A. hypochondriacus proved to have the best agronomic traits and the seeds had the best nutritional value (high protein and starch content and a good fatty acid profile), being potential ingredients for pig diets. Mihaila et al. [22] investigated the possibility of substituting soybean meal in pig feed with guar meal, which is a by-product rich in protein and carbohydrates, obtained after mechanical separation of the endosperm from the germ and coat of guar seeds. The obtained results demonstrated that guar flour can replace 100% soybean meal in a pig finishing diet, without changing animal performance or carcass traits, and can have a positive impact on the main greenhouse gas emissions resulting from enteric fermentation (E-CH₄) and manure (M-CH₄ and NO₂).

Food safety, the environment, and public health are threatened by farmers’ overuse of veterinary antimicrobials. Based on data collected from 675 swine farms in China, Si et al. [23] reported that the main factors involved in this phenomenon are a lack of access to valid information or skill constraints, as the Internet has become the main source of information for young farmers. The authors consider it necessary to standardize the use of antimicrobials by farmers through the intervention of governmental bodies and the application of sustainable agricultural policies.

In response to the growing emphasis on the quality of products of animal origin, Frunză et al. [24] investigated the effect of gender and muscle type on the fatty acid profile, health lipid indices, texture, color, and sensory quality of rabbit meat. Research has shown that male meat was healthier (richer in essential fatty acids, with a better ratio of hypo-/hypercholesterolemic fatty acids and lower values of atherogenic indices (AIs) and thrombogenic indices (TIs)). The flesh of females was more tender but less pigmented than that of males, while overall sensory attributes were better in males. The authors recommend slaughtering females 3–4 weeks earlier than males in order to avoid excessive fat deposition and, consequently, the development of unfavorable lipidic indices for consumers’ health. The studies carried out by Albu et al. [25] also fall under the same theme, evaluating the quality of multifloral honey from the northeast of Romania. The analyzed honey samples were distinguished by a high content of antioxidants (phenols and flavonoids), confirming its therapeutic character. The predominant minerals in the honey were K, Ca, and Na, and in a limited number of samples the Pb content was above the detection limit but within the limit recommended by the legislation. The use of the FTIR spectral method confirmed the difference between the samples, investigated through pollen analysis, and highlighted the differences in the chemical composition of the honey.

The preference and orientation of consumers towards ‘natural products’ have encouraged many farmers to introduce grazing in the management of dairy farms, as it has a positive impact on the content of nutrients and bioactive compounds in milk but also on the health and behavior of dairy cows. The studies carried out by Blaga Petrean et al. [26] showed that the general welfare of dairy cows improved when they had access to pasture, proving the superiority of this management system that allows cows to exhibit a wide range of natural behaviors.

The decrease in the genetic diversity of animal populations imposes the need to conserve endangered species in order to maintain the biodiversity of animal genetic resources. In this sense, the study by Davidescu et al. [27] had the main aim of highlighting and comparing the most recent articles on the origin, evolution, genetic diversity, and phylogenetic relationships of Podolian cattle, with special emphasis on the endangered Romanian Gray Steppe breed, whose importance is given by the special biological properties it possesses (adaptability and resistance against diseases and to severe climate and habitat conditions, and longevity). The breed should be well preserved for the improvement of other cattle and for the protection of biodiversity. The authors propose taking immediate measures and allocating adequate financial resources to conserve the valuable genetic diversity of Romanian Gray Steppe cattle, which still represent a valuable genetic pool.

In 2022 we proposed to produce a second volume of the Animal Nutrition and Production Special Issue; here, we have succeeded, let us say with more success—the second edition has 23 published articles compared to only 20 in series I. The audience created by the second Special Issue also indicates that nutrition and animal productions are of interest to researchers from all over the world. This time, the range of addressed topics was very varied and very interesting, as indicated by the large number of views on the second series (over 27,000 at the time of publishing this Editorial). We thank the Editorial Board of the Agriculture journal and the Farm Animal Productions section for allowing us to collaborate and complete the second Special Issue of Animal Nutrition and Productions: Series II.